431 TIIK CHICAGO ACADEMY (i| S( II.XCES. 



Shell: Elongated, compressed, thin; color spermaceti white, 

 sometimes brownish-white; surface shining, marked by heavy, raised 

 close-set growth lines which are crossed by fine impressed spiral lines, 

 the surface frequently malleated; whorls six or seven, strongly angu- 

 lated at the shoulder and flattened on the side, the body whorl much 

 contracted, strongly shouldered and flattened in the middle ; spire long, 

 turreted, tapering; nucleus small, ovate, smooth, resembling jackson- 

 ensis in outline; sutures well impressed; aperture long and narrow, 

 contracted, in some specimens being almost continuous by the eleva- 

 tion of the inner lip; the aperture occupies a little less than half the 

 entire length of the shell; outer lip thickened within by a longitudinal 

 varix ; inner lip rather broad, strongly reflected and appressed to the 

 parietal wall and the umbilical region, usually leaving a very small 

 chink but frequently entirely closing the perforation; the inner lip is 

 tightly appressed at its junction with the parietal wall producing a well- 

 marked plait ; in some specimens the inner lip emargins the umbilical 

 chink, much as in emarginata; axis twisted. 



Length. 



Width. 



Aperture ler 



igth. 



Width. 



22.00 



8.50 



10.60 





3.75 mill, 



19.25 



8.00 



9.75 





4.50 " 



16.75 



7.50 



8.50 





3.25 " 



16.50 



6.50 



9.00 





2.75 " 



Types: Collection Bryant Walker, No. 11995. 

 Type Locality : Higgins Lake, Michigan. 

 Animal, Jaw, Radula and Genitalia : Unknown. 

 Range : Michigan. A species of the Canadian region and of the 

 Boreal (Canadian) life zone. 



RECORDS. 



Michigan: Higgins Lake, Roscommon Co. (Currier; Walker). 



Geological Range : Unknown. 



Ecology: "This species has never been found alive so far as I 

 know. It is probably as inhabitant of deep water that only comes to 

 shore occasionally and apparently no one as yet has been fortunate 

 enough to strike the occasion." (Walker). 



Remarks : Contractu is a distinct, easily recognized species, dis- 

 tinguished by its long, acute spire, shouldered zvhorls, compressed body 

 whorl and heavily plaited columella. Its very narrow, compressed 

 shell and very long and narrow aperture separate it from emarginata, 

 to which it is related. It approaches some forms of emarginata can- 

 adensis, but is always narrower and thinner. The peculiarly contracted 

 aperture, which is sometimes reduced to a mere slit, and its notably 

 compressed and shouldered body whorl, are its principal distinctive 



